/* day_mon2.c -- 让编译器计算元素个数 */
#include <stdio.h>
int main(void)
{
     const int days[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31 };
     int index;

     for (index = 0; index < sizeof days / sizeof days[0]; index++)
          printf("Month %2d has %d days.\n", index + 1, days[index]);

     return 0;
}